Well, I'm not positive they're really experts; the following white paper
says they're using a factor of 10X too low for the solubility/phase
separation point--0.05% vis a vis 0.5%. I'm inclined to believe the
latter over the former as being "more expert".
Even if the former were correct, it's still only 2.5% of the saturation
volume in 100% RH air if were to condense it all. I'd be willing to
listen if somebody could recompute independently and show gross error in
the above estimate.
If it were such a problem as the above reference claims, it'd be
happening all over the US in such high numbers there'd be no way the
issue couldn't be addressed. I think they're simply over-reacting to
the possibilities of clean fuel contamination. _Getting_ contaminated
fuel from a service station, otoh, does happen fairly regularly owing to
water entrance into USTs by various mechanisms or other ways of
introducing water in bulk into supplies. But starting with clean fuel
in a vehicle tank from condensation? Nah, ain't agonna' happen...
(PDF DOC link to a readable white paper on the subject by vendor of
prevention/mitigation systems for bulk suppliers)
Well, as noted before, I wasn't convinced by their analysis having done
the calculation so I kept looking and found another white paper; this
one by EPA
It draws the same conclusions I did--
"Phase separation, however, generally only occurs when liquid
water (as opposed to water vapor) is introduced to the fuel
system. If tank vents are left open, either in the engine being
operated, or at a fuel distribution station, water can enter the
fuel system in the form of rain (or spillage, etc.) or through
the air in the form of moisture. Also, since conventional
gasoline absorbs very little water, there is often a layer of
water present at the bottom of a filling station tank normally
used to store conventional gasoline (water is more dense than
gasoline, and will therefore sink to the bottom). Before an
oxygenated gasoline is added to such a storage tank for the first
time (particularly ethanol-blended fuels), this water must be
purged from the tank to prevent the water from removing any
ethanol from the fuel.
Since the solubility of water in both gasoline and air
decreases with a decrease in temperature, water can enter a fuel
system through condensation when the atmospheric temperature
changes. For example, assume a tank containing conventional
gasoline contains only one gallon of fuel. Assume also that it
is closed while the outside temperature is 100 degrees F with a
relative humidity of 100 percent. If this tank is left sealed
and the temperature drops to 40 degrees F, water will likely
condense on the inside of the tank, and dissolve in the fuel. In
order for enough water to condense from the air to cause
gasoline-water phase separation, however, there must be
approximately 200 gallons of air per gallon of fuel over this
temperature drop (100 to 40 degrees). Since oxygenated fuels can
hold even more water than conventional gasoline, it is even more
unlikely that enough water will condense from the air to cause
gasoline-water phase separation."
The 200:1 ratio almost precisely duplicates my earlier estimate...I just
quoted it over a differing volume and in alternate units. I did note
that while I hadn't computed it, the 3.8 tsp measurement your reference
used is referred to in this document but they mis-computed/mis-typed the
percentage in the 0.05%; it is 0.5%.
So, anyway, the problem of phase separation in E10 of initially clean
fuel in a clean tank occurring owing to moisture condensation from the
air introduced alone is simply a non-issue.
On Saturday, August 6, 2016 at 9:27:44 PM UTC-4, Bill wrote:
minimum price for a aftermarket in tank pump assembly 300 to 400 bucks.
for a brand new OEM pump at least 600 bucks and often more. pumps include fuel gauge and fuel filter. the gasoline in the tank cools the pump. run the tank low or out, espically in hot weather, fries the pump.......
my 1969 impala had a fuel pump fail, a easy replacement bolted to the engine.. i think it cost 40 bucks
far cheaper to always keep the tank at least half full.
but its your money and your back, feel free to replace them as often as you want..........
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